Hi
1. If the goal is to shift the boundaries onto a coarse grid, why round *down* for longitudes and *up* for latitudes? Why not round in the same direction for both?
Even though I made that change (originally it rounded down/up in the same way as your patch). I have no idea why one goes up and the other down! Probably no good reason.
Finally, I am wondering how important the rounding is. It seems that mkgmap will happily process arbitrary .osm files, including those that never passed through the splitter and thus do not have rounded boundaries. Would it be possible to leave out the rounding? Or is it needed for inter-tile routing for example?
For routing to work across tiles the nodes at the edge of the tile must match exactly (or within a few units at least) the edge node of the same road in the adjacent tile. The page: http://www.mkgmap.org.uk/page/17 gives some background on the original design. The point about rounding to the course boundaries is not true from the point of view of the Garmin format. At the time I didn't know how to make it work without putting them on course boundaries, but now we probably could. In general the tiles can have completely arbitary boundaries that follow a country border for example, but this would need corresponding support in mkgmap. ..Steve